Department of Health Sciences, University of L'Aquila, Italy.
Hippocampus. 2012 May;22(5):1154-63. doi: 10.1002/hipo.20961. Epub 2011 Jul 7.
Posttraumatic stress disorder (PTSD) is characterized by the presence of anatomo-functional hippocampal alterations. To date, the ability to orient within the environment, which relies on hippocampal integrity, has never been investigated in PTSD. We hypothesized that the ability to form a cognitive map of the environment would be impaired in PTSD. Moreover, spatial memory consolidation benefits from postlearning sleep. Because PTSD individuals often complain about sleep disturbances, we hypothesized that any sleep effect on memory performance would be hampered in these subjects. Twenty-two subjects, all survivors of the L'Aquila 2009 earthquake, were divided into a PTSD and a control group, based on clinical evaluation. After an acquisition phase, they were tested twice ("test" and "retest") on a virtual navigation task. In addition, participants were administered the Digit Span and Task Switching. Subjective sleep quality and sleep disturbances were also assessed. The two testing sessions were on consecutive mornings, interspersed with a night of sleep. During the acquisition phase, the PTSD group took more than twice as long to form a cognitive map of the environment compared to the control group. However, once this phase was successfully completed, the two groups did not differ at test, but they tendentially differed at postsleep retest. Additional analyses comparing performances between groups on test-retest difference scores confirm that sleep-dependent consolidation may be differentially affected in the two groups. Our findings are strictly confined to the navigation performance, excluding a generalized cognitive deficit. PTSD also reported more subjective sleep disturbances and shorter sleep time than controls, which were correlated to worse performance at retest. The specific deficit in the formation of a cognitive map reported in PTSD may be related to hippocampal dysfunctions as well as to the sleep disturbances experienced by these patients. The possible deficiency of sleep-dependent spatial performance improvement should however be confirmed by further studies comprising a wake control group.
创伤后应激障碍（PTSD）的特征是存在解剖功能海马改变。迄今为止，依赖于海马完整性的环境定向能力从未在 PTSD 中进行过研究。我们假设环境认知图的形成能力会在 PTSD 中受损。此外，空间记忆巩固受益于学习后睡眠。由于 PTSD 患者经常抱怨睡眠障碍，我们假设这些患者的任何睡眠对记忆表现的影响都会受到阻碍。22 名受试者均为拉奎拉 2009 年地震的幸存者，根据临床评估分为 PTSD 组和对照组。在获得阶段之后，他们在虚拟导航任务上进行了两次测试（“测试”和“复测”）。此外，还对参与者进行了数字跨度和任务转换测试。还评估了主观睡眠质量和睡眠障碍。两个测试会话在连续的早晨进行，中间间隔一夜睡眠。在获得阶段，PTSD 组形成环境认知图的时间是对照组的两倍多。然而，一旦成功完成此阶段，两组在测试时没有差异，但在睡眠后复测时差异趋势明显。比较组间测试-复测差异分数的进一步分析证实，睡眠依赖性巩固在两组中可能受到不同影响。我们的发现严格限于导航性能，不包括一般认知缺陷。PTSD 还报告了比对照组更多的主观睡眠障碍和更短的睡眠时间，这与复测时的表现更差相关。PTSD 中报告的认知图形成特定缺陷可能与海马功能障碍以及这些患者经历的睡眠障碍有关。然而，睡眠依赖性空间性能改善的可能缺陷应通过包括清醒对照组的进一步研究来确认。
